Inertia ring for suppression of driveshaft radiated noise

Abstract

A combination of an inertial body and a shaft including an elongated hollow member having a vibration characteristic that includes a bending mode and a breathing mode, the bending mode vibration characteristic and the breathing mode vibration characteristic having closely coupled resonance frequencies. An inertial body is attached to the elongated hollow member in the proximity of a bending mode vibration antinode to decouple the bending mode resonance frequency from the breathing mode resonance frequency.

1 . A combination of an inertial body and a shaft comprising: 
 an elongated hollow member having a vibration characteristic including a bending mode and a breathing mode, the bending mode vibration characteristic and the breathing mode vibration characteristic having closely coupled resonance frequencies; and    an inertia member of predetermined mass attached to the elongated hollow member proximate a bending mode vibration antinode to decouple the bending mode vibrational resonance frequency from the breathing mode vibrational resonance frequency.    
   
   
       2 . The combination according to  claim 1 , wherein the elongated hollow member is a driveshaft.  
   
   
       3 . The combination according to  claim 1 , wherein high frequency gear transmitted errors from either a transmission or an axle cause an expansion and contraction of the elongated hollow member in the breathing mode.  
   
   
       4 . The combination according to  claim 1 , wherein high frequency gear transmitted errors from either a transmission or an axle cause an oscillation of the elongated hollow member in the bending mode.  
   
   
       5 . The combination according to  claim 1 , wherein the inertia member is attached to the elongated hollow member proximate a bending mode vibration antinode nearest an end of the elongated hollow member.  
   
   
       6 . The combination according to  claim 1 , wherein the inertia member is fixed to the elongated hollow member using a press fit.  
   
   
       7 . The combination according to  claim 1 , wherein the inertia member includes two separate halves, the inertia member being affixed to the elongated hollow member by clamping the two halves to the elongated hollow member.  
   
   
       8 . A driveshaft for torque transmission purposes especially for use in a drivetrain of a motor vehicle, the drive shaft comprising: 
 a shaft having first and second ends and a central region;    an inertia ring fixed at a bending mode antinode on the shaft, the inertia ring decoupling a closely coupled bending mode vibrational resonance frequency and breathing mode vibrational resonance frequency to reduce the amplitude of shaft vibrations whereby the amount of noise emitted by the driveshaft is reduced.    
   
   
       9 . The driveshaft according to  claim 8 , wherein the inertia ring is fixed to the shaft at a bending mode antinode nearest a rear axle.  
   
   
       10 . The driveshaft according to  claim 8 , wherein the inertia ring has an inner diameter and wherein an outer diameter of the shaft is greater than the inner diameter of the inertia ring so that the inertia ring may be press fit onto the shaft.  
   
   
       11 . The driveshaft according to  claim 8 , wherein the inertia ring is securely fixed to the shaft and does not oscillate or vibrate independently from the driveshaft.  
   
   
       12 . The driveshaft according to  claim 8 , wherein the inertia ring is rotationally symmetrical.  
   
   
       13 . The driveshaft according to  claim 8 , wherein the weight of the inertia ring is determined by finite element analysis of the drivetrain.  
   
   
       14 . The driveshaft according to  claim 8 , wherein the inertia ring is made of aluminum.  
   
   
       15 . The driveshaft according to  claim 8 , wherein the inertia ring is made of steel.  
   
   
       16 . The driveshaft according to  claim 8 , wherein the weight of the inertia ring is determined by testing.  
   
   
       17 . A drivetrain for a vehicle having an engine, transmission, differential and driveshaft connection wherein the driveshaft connection comprises: 
 a shaft having first and second ends and a central region;    an inertia ring having an inner opening fixed at a specified point on the shaft to decouple the frequency at which bending mode vibrational resonance occurs from the frequency at which breathing mode vibrational resonance occurs to reduce the amplitude of driveshaft vibrations and to limit the amount of noise emitted by the driveshaft.    
   
   
       18 . The drivetrain according to  claim 17 , wherein the inertia ring is fixed at an antinode.  
   
   
       19 . The drivetrain according to  claim 17 , wherein an outer diameter of the shaft is greater than an inner diameter of the inertia ring so that the inertia ring may be press fit in place at a desired location corresponding to an antinode.  
   
   
       20 . The drivetrain according to  claim 17 , wherein the inertia ring is securely fixed to the shaft and does not oscillate or vibrate independently from the driveshaft.